The present invention relates to an electronic apparatus having a cooling system of a heat-generation element thereof.
Disclosure is made on the structure of a conventional liquid cooling jacket for use in an electronic apparatus, for example, in the following patent documents 1 and 2.
In those patent documents 1 and 2, for the purpose of making an improvement of heat conductive performance or capacity on the liquid side, there is shown the structure, in which a plate-like cooling fin is provided or an injection nozzle is provided, within a cooling liquid passage thereof. For forming the cooling fin, in general, the cutting process is used in many cases; therefore it rises up labor and manufacturing costs necessary for that processing thereof.
On the other hand, with a method for processing with relatively low costs, such as extruding process, for example, but there is a limit in the height and the pitch of the fins, which can be processed; therefore, it is difficult to maintain the cooling performance or capacity thereof to be favorable.
Also, with the structure of providing the injection nozzle, it increases the thickness of the liquid cooling jacket; therefore it is difficult to apply it, in particular, into a narrow space.
In the following patent document 3, there is disclosed a heat sink, being constructed by piling up lamination plates in a direction of the thickness thereof. However, this patent document 3, since it pays the consideration onto, mainly, such as preventing the generation of defects, and/or improvement on an evenness of temperature within the flow passages, therefore there is made no mentioning about a promotion of heat transfer, through an increase of the heat transfer area within the flow passage itself and/or an improvement on the heat transfer coefficient thereof.
In the following patent document 4, there is disclosed the structure of a heat sink, applying a lamination plate formed by the press processing. However in the patent document 4, there is made no mentioning about the promotion of heat conductivity or transfer within the flow passage itself.
In the following patent document 5, there is disclosed the structure of a liquid cooling heat sink, in which an inner fin is inserted therein, for obtaining the promotion of heat transfer of the flow passages itself. However, with the patent document 5, since a brazing material is put therebetween, which has remarkably low heat conductivity, then heat transmission in the direction perpendicular to a base surface is obstructed at this portion, and therefore it is impossible to obtain such the inner thermal resistance that can be obtained when it is formed into a one body, which is processed through the cutting process.
Patent Document 1: Japanese Patent Laying-Open No. Hei 8-279578 (1996), in particular page 5 and FIGS. 1–5;
Patent Document 2: Japanese Patent Laying-Open No. Hei 8-31994 (1996), in particular pages 6–7 and FIGS. 1–4;
Patent Document 3: Japanese Patent Laying-Open No. Hei 9-102568 (1997), in particular page 4 and FIG. 1;
Patent Document 4: Japanese Patent Laying-Open No. 2003-7944 (2003), in particular pages 2–3 and FIG. 2; and
Patent Document 5: Japanese Patent Laying-Open No. 2002-170915 (2002), in particular pages 2–4 and FIGS. 1–5.
As was mentioned above, it must be said that the structure is already known, in which a thin films made of a metal are laminated in the thick direction, so as to form a flow passage within an inside thereof, in the patent document 3 mentioned above.
However, this patent document 3 never mention about the promotion of heat transfer of the flow passage itself.
Thus, a purpose of that invention disclosed in the patent document 3 is to prevent a heat sink of lamination plate type from generating the defects therein, and also to obtain an improvement on reliability and cooling capacity of an apparatus or equipment, by installing that heat sink therein, as was described in the column “Problems to be Solved” in the specification thereof.
And, in the patent document 3, a pair of end plates are provide, for holding a flow passage plate and a communicating plate from both sides thereof, and further they are disposed at positions corresponding to the flow passage of high temperature and that of low temperature, thereby achieving an averaging of temperature.
In this manner, though the patent document 3 talks about an improvement on the cooling capacity, however it is impossible to promote or enhance the heat conductivity of the heat sink by itself.